This invention generally relates to metallurgical casting processes, and more specifically to a method and apparatus for providing a flaskless mold having removable chills.
Casting processes for forming molded or cast articles can employ a vertically potted or horizontally potted mold. A horizontally potted mold traditionally is formed from an upper portion called a cope and lower portion called a drag. A vertically potted mold comprises two halves abutted to each other and generally defining or forming a cavity between the two halves for receiving a molten metal. Additionally, molded articles may be formed by using either a cast iron flask-type mold or a flaskless mold typically comprised of sand and a binder.
Typically, the mold cavity will have features or reliefs formed within mold walls defining the cavity to form desired details or impressions and cavities in the molded articles. For example, such details can form ports and other features of cylinder heads or cylinder blocks. A sand core may also be added to the mold casting to impart further detail to the molded article such as defining contours and interior features within the metal castings. These cores are often comprised of sand and a suitable binder material and are set within the mold cavity prior to the closing of the mold.
Furthermore, metal objects called chills may be placed on the outside or inside of a mold cavity to induce more rapid cooling at the point of insertion or placement. Chills may be used to selectively develop different metallurgical properties throughout portions of the molded article and/or to impart patterns or relief details to the molded article. Typically, the chill is received in a recess formed within the mold cavity and is positioned in the mold such that it will contact the molten metal entering the mold cavity. The chill is placed into the mold before the two halves forming the mold cavity are joined. Once the mold is closed, molten metal is introduced into the mold cavity. The chill cools the molded article in contact with the chill and hardens the area of the molded article immediately adjacent to the chill.
Once the molded article has solidified, both the article and chill generally are removed from the mold by a xe2x80x9cshakeoutxe2x80x9d process or other process where the mold is broken apart and the sand removed. The chill, sand cores and mold are removed from the molded article at the same time. The chill inserts are recovered along with the waste sand that formed the mold. After the chills are recovered, they must be cleaned before being reused. Additionally, the chills can be damaged in the removal process and must be inspected for damage before being reused. Furthermore, recovering the chills with the waste sand requires a surplus of chills, since chills must first be sorted out from the waste sand.
Therefore, there is a need for a process and apparatus for forming molten articles that address the foregoing and other known and unknown problems in the art.
Briefly described, the present invention comprises both a process and apparatus for forming a molded article. The molded article generally is formed in a vertically potted flaskless mold. A chill is placed into the mold after the mold is closed to direct the cooling of the molded article at a desired area or section of the article. Molten metal is introduced into the mold cavity and allowed to solidify. After solidification, but before the mold is broken down, the chill is removed.
In an embodiment, the method of forming a molded article includes providing a flaskless mold with at least one opening formed or defined in the mold. A chill is placed within the opening to direct the cooling of the molten metal that is introduced into the mold. The chill is then removable from the mold, through the defined opening, before the mold is destroyed. The chill may then be readied for reuse in additional casting operations.
In a further embodiment, the method of forming a molded article includes forming a flaskless substantially vertically potted sand mold with an opening formed in the top portion of the mold. A chill is then placed within the opening for generally directing and/or enhancing the cooling of the molten metal introduced into the mold, at desired portions or sections of the molded article. The chill is then removed before the mold is destroyed.
Additionally, the invention includes a flaskless mold assembly for producing a molded article. The mold assembly includes a first portion having a top surface and a mold joint surface and a second portion having a top surface and a mold joint surface. A mold cavity is defined by at least a part of the mold joint surfaces of the first and second portions. The mold joint surfaces are abutted to one another in a substantially vertical plane forming a vertically potted joint. An opening is formed in the top surfaces of the abutted first and second portions. A chill is then removably positioned or received within the opening of the abutted first and second halves. The chill can then be removed from the mold assembly without substantially destroying the mold.
Various objects, features, and advantages of the present invention will become apparent upon reading and understanding this specification, taken in conjunction with the accompanying drawings.